Chitosan nanoparticles can be prepared by the
interaction of oppositely charged macromolecules.
Tripolyphosphate (TPP) has often been used to
prepare chitosan nanoparticles because TPP is
nontoxic, multivalent and able to form gels through
ionic interactions. The interaction can be controlled
by the charge density of TPP and chitosan, which is
dependent on the pH of the solution.